PGP and cancer: In 1995, Tishler et al. (77) found that MDR1 mRNA was overexpressed in brain tissue resected from patients with refractory epilepsy and postulated the transporter hypothesis of refractory epilepsy: P-gp overexpression at the blood–brain barrier in epilepsy decreases ASD brain uptake, thus causing ASD resistance similar to pharmacoresistance in cancer (2).